Stephen Splits with Hayden Panettiere!

Just weeks after her 18th birthday, Hayden Panettiere is back on the market. Us Weekly reported this week that Heroes star Hayden and boyfriend of a year, Laguna Beach alum Stephen Colletti, 21, have split.

The actress, who spent much of the past few weeks abroad in Europe with Heroes co-stars on promotional duties, seems to be dealing well - in fact, remarkably so - with the recent breakup. When asked by Us Weekly of Stephen's whereabouts at the VMA's on September 9, she furrowed her brow and said, "I don't know. In California?"

However, Us reports that Hayden may have seen the break-up coming for quite a while. A source said, "Their breakup has been a long time coming."

Amicable or not, Panettiere seems confident in a remaining firm friendship with Colletti. "We are still very close friends," she told Us, "and talk to each other frequently. We appreciate and support each other's careers."

Stephen was not available for comment.